A novel microdissection model for probing cellular interactions. V. Free Mannan

Abstract

The adhesion between the NIH model sea urchin embryo roof of the blastocoel and tip of the archenteron is a cellular interaction that has interested investigators for over a century, yet its molecular basis is unknown. Here, 102 blastocoel roofs and archenterons were microdissected out of 102, 54 hr Lytechinus pictus embryos that adhered to each other when placed together. 25 mg per ml free mannan was added to the adhered roofs and archenterons. They remained adhered and then were pulled apart and placed together again in the free mannan solution. All 102 roofs and archenterons adhered once again, the mannan possibly bridging mannan‐binding receptors on both components. As reported in Part III of these studies, mannan conjugated agarose beads also adhered to the dissected roofs and archenterons and here this work was extended to 65, 54 hr L.pictus embryos. Part I of these studies indicated that alpha methyl mannose blocked the cellular interaction. Part II of these studies showed that mannose‐binding lectins could block the interaction. Taken together, this set of studies suggests that mannose‐containing glycans and mannose‐binding receptors may be involved in the cellular interaction between the archenteron and blastocoel roof. This microdissection method, that removes the components of adhesive events from intact embryos, is novel and likely to lead to a better understanding of the molecular basis of cellular interactions (supported by NIH NIGMS SCORE S0648680, MARC, RISE, the Joseph Drown Foundation, the Sidney Stern Memorial Trust, and CSU Northridge Biology FIRE course funding).